Automatic thread grinding machine



March 18', 194.7.

H.'N. SEYFERTH EVAL AUTOMATIC THREAD GRINDING MACHINE Filed Dec. 30. 1941 14 Sheets-Sheet 1.

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H. N. SEYFERTH ET AL AUTOMATIC THREAD GRINDING' "MACHINE Filed Dec. so, 1941 14 sheets-smet s fas 3?/ +6 36 f/zveafors Harold/K6 March 18, 1947. l H. N. sEYFERTl-l r-:T A1. 4 2,417,707

AUTOMATIC THREAD GRINDING MACHINE Filed Deo. 30, 1941 I 14 Sheets-Sheet 4 fw 41,7 @fur M4K-.42 CT-romys March 18, 1947.

H. N. SEYFERTH ETAL A 2,417,707

AUTOMATIC THREADk GRINDING MACHINE Filed Dec. 3o, 1941 14 Sheets-Sheet 5 fr? 21e/fors /Ycz/oZcZ/V leyfer Elgyf'do/zf Cork fave, P' K Womans March 18, 1947. A H. N. sEYFERTi-l l-:T AL 2,417,707

AUTOMATIC THREAD GRINDING MACHINE Filed Dec. so, 1941 14 sheets-snaai e Marchnl8, 1947. H. N. sx-:YFERTH ET AL 2,417,707

AUTOMATIC THREAD GRINDING MACHINE .Filed Deo. so, 1941 14 sheets-sheet fr TrozzLnf/J March 18, 1947. H. N; sEYFERTl-l ETAI. 2,417,707.

AUTOMATIC THREAD GRINDNG MACHINE March 18, 1947. H. N. sEYFx-:RTH ETAL 2,417,707

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Maldl 13, 1947. H. N. sr-:YFERTH ET AL 2,417,707

AUTOMATIC THREAD GRINDING MACHINE Filed Dec. 30, 1941 14 Sheets-Sheet ll Awiv March 18, 1947. H. N. sEYFERTH ET Al.

, AUTOMATIC THREAD GRINDING MACHINE Filed Dec. 30, 1941 14 Sheets-Sheet l2 .snm ZU@ ff@ N, M

March 18, 1947. H. N. sEYFERTl-l ETAL AUTOMTIC THREAD GRINDING MACHINE flut 6R25' vfwventaks )fara/d 72. Seg/farti I Gordan Cor/c March 18, 1947. H'. N. sEYFERTl-i ETAL A 2,417,707

AUTOMATIC THREAD l GRINDING MACHINE Filed Dec. so, 1941 14 sheets-sheet 14 Patented Mar. 18, 1947 AUTOMATIC THREAD GRINDIN G MACHINE Harold N. Seyferth, East Detroit, and Gordon Cork, Detroit, Mich., assignors to Ex-Cell-O Corporation, Detroit, Mich., arcorporation of Michigan Application December t0, 1941, `Serial No. '424,984

The invention relates to machine tools and has particular reference to improvements in thread grinding machines of the automatic type.

One of the objects of the invention is to prvide a novel thread grinding machine with an automatic operating cycle in which the grinding wheel is operated selectively at different speeds of rotation at various times, for example, at one speed for rough grinding, at another speed for iinish grinding, and at a third speed for Wheel dressing.

Another object is to provide a new and improved thread grinding machine having a wheel dressing device and an automatic cycle in which the device is arranged selectively t0 dress the wheel after any given number of grinding passes, or after any given number of Workpieces have been ground.

Other objects and advantages will become apparent as the description proceeds.

In the accompanying drawings,

Figure 1 is a front elevation oi a machine tool embodying the features of the invention,

Fig. 2 is a side elevation of the machine as seen from the left-handend of Fig. 1.

Fig. 3 is a plan View of the machine.

Fig. l is a horizontal sectional view of a part of the machine taken along the line 4-4 of Fig. l.

Fig. 5 is a vertical sectional view taken substantially along the line 5-5 of Figfl.

Fig. 6 is a sectional View illustrating a detail of the mechanism which controls the movement of the grinding wheel in cutting a taper thread and is taken along the the line 6--6 of Fig. 3.

Fig, l is a fragmentary rear View illustrating the supporting means for the grinding wheel assembly and dressing device. I

Fig. 8 sho-ws in perspective and somewhat diagrammatically means for controlling the relationship of the grinding wheel and the dressing device.

Fig. 9 is a View in vertical axial section through the Work head or headstock and is taken along the line 9--5 of Fig. 2.

Figs. l0 and 11 are transverse sectional views through the Work head or headstock taken along the lines indicated by the numerals |0.l0 and ll-ll in Fig. 9.

Fig. 12 is apartial sectional view taken on a 1'5 Claims.

vertical plane through the axisof the grinding wheel spindle substantially along the line lZ-IZ in Fig.'3.

Fig. 13 is a transverse-sectional View through the grinding wheel spindle assembly taken along the line |3-I 3 of Fig. 12.

Fig. 14 is a transverse sectional View of the machine taken along-the linelll-M of Fig. 1`

Fig. l5 is an enlarged fragmentary :front elevation of thecontrol mechanisms located on the right-end portion of the machine as viewed in Fig. 1.

Figs. .16 and 17 are vertical sectional views taken respectively along vthe lines IG--l and Il-H in Fig. 15.

Figs. 18 and 19 are detail sectional views taken respectively along the lines 18e-I8 and `lll- Iain Fig. 1.6.

Fig. 20 vis one portion of the wiring diagram for the control and motor supply system for the machine.

Fis'.21 is ano-ther portion of the wiring diagram.

Fig. 22 is still another `portion of the wiring diagram.

Machine structure 21 with a driveshaft for the grinding Wheel,

and a reversible-dressenmotor 29 also located at the rear .of the base andconnectedbyaheXible shaft 30 with the driven elementslofthedressing device. The vthird motorl (Fig. 2.) is a reversible `feedrnotor for revolving the Work being threaded and ltraversing it past `the grinding wheel, and is yconnected kry-a beltdrive `32 and stepped cone pulleys '3-3with Va drive shaft 34 V(Figsil and 10) for the :Work shaft35. A fourth motor 2lia drives a coolant pump (not shown) to supply coolant to the wheel during grinding. Certain additional motors are included in the machine for use in the automatic cyclic operation, but they will be described later.

In the operation of the machine, the work 24 (Fig. 1) is traversed endwise and revolved in timed relation so that the grinding wheel engaging its periphery forms in the work a thread of correspondingly controlled pitch. The wheel is fed toward the work to determine the depth of cut, and is intermittently dressed by the dresser mechanism 25.

The relationship of the grinding wheel and the dressing device, and of the grinding wheel and the work, are controlled simply and conveniently from the operators station at the front of the machine. The adjustment devices used during manual or non-automatic operation of the machine include a feed control means 36 by which the operator may set the machine to produce a predetermined depth of cut in the workpiece, control the feed of the grinding wheel into the workpiece, or quickly retract the grinding Wheel out of engagement therewith. The adjustment mechanisms also include a dressing device control means, generally designated as 31, by which a dressing relationship of the dressing device to the grinding wheel is obtained, and this means also'includes means for effecting a compensating adjustment of the grinding wheel to the workpiece, whereby-an initial relation of the grinding wheel and workpiece remains fixed regardless of the number of dressing operations or the variation n the diameter of the grinding wheel resulting from the removal of abrasive in the-dressing operation. The adjustment means further include means, designated generally as 38, for adjusting the machine to grind straight or tap-ered screw threads.

The three main adjustment means outlined above are, as will hereinafter be more particularly described, interrelated by a novel arrangement of three superimposed slides arranged for conjoint as well as relative movement and com-- Drising (as shown in Fig. 5) a lower slide 39, an intermediate slide 40, and an upper slide 4 I. The slides for convenience will hereinafter be termed the taper slide 39, the wheel slide 40 and the dresser slide 4|. The three slides have parallel movement in a front to rear direction of the machine base, i. e. transverse to the axis of the work 24. Thus, as shown in Fig. 12, the-base has a plate 42 (see also Fig. 5) rigidly secured thereto beneath the taper slide 39 and ways 43 on the plate support the taper slide. On the upper surface of the taper slide 39 are ways 44 supporting the wheel slide 40 and on the upper surface of the Wheel slide are ways 45 supporting the dresser slide 4l. This superimposed relation of the slides results in conjoint movement of them. Thus, when the lowermost or taper slide 39 is advanced or withdrawn, the wheel and dresser slides 40, 4I move with it. Similarly, when the wheel slide 40 is advanced or withdrawn (over the taper slide), the dresser slide moves with it in addition to the wheel assembly on it. Finally, the dresser` slide 4l can be advanced or Withdrawn independently of the other two slides.

The actuating means for moving the taper slide will be described first, particular reference being made to Figs. l, 4 and 6. This taper slide is, in brief, arranged to be moved in timed relationto the work slide 41 carrying the head and tailstocks betweenwhich the Work 24 is received. lIt may be noted here that this work slide is mounted on longitudinal ways I5l on the upper surface of the base so that the work slide has a reciprocatory movement as will hereinafter be explained to feed the workpiece 24 in a path generally paralleling the axis of the grinding wheel. To actuate the taper slide for ordinary taper thread cutting, a sine bar 48 is positioned on the front face of the work slide 41, pivoted thereto on a hori- Zontal axis as at 49 through one end of the sine bar. The sine bar is adjustable to vary its angle of inclination relative to the reciprocatory movement of the work slide 41 by such means as a worm 59 supported in a housing 5I on the work slide for engagement with a rack segment 52 on the free end of the sine bar. A shouldered screw 53 engaging the work slide 41 and extending through a coacting arcuate slot in the end of the sine bar, holds the latter in any position of adjustment. The lower side of the sine bar 48, in its movement with the work slide 41, rides over the upper end of a vertically slidable plunger 54 (Fig. 6) supported by a bearing '55. The lower end of the plunger engages one arm of a bell crank lever 56 which ispivoted as at 51 to a support 58, the other end of the bell crank lever being in engagement with the front end of a rod 59, and as shown inFig. 4, it extends rearwardly through the taper slide 39 and through the rear side of the base. Through the medium of the mechanism nextdescribed below, oscillation of this bell crank is used to shift the taper slide.

A wing nut G engages the rearwardly projecting end of the shaft 59 and a spring 6I encircles the rear portion of the shaft and bears between the rear wall of the base and the adjacent side face of the taper slide 39. This spring is tensioned to urge the taper slide forwardly. Extending across the front of the taper slide is a wiper plate 62 having an elongated sleeve 63 secured thereto and encircling the rod 59. The forward end of the sleeve 53 has external screw threads thereon for engagement by a nut 64 which is rigid with a gear 95. An elongated collar 66 secured to the sleeve 63 encloses the end of the nut 54 as well as a spring 61 which is seated against a shoulder on the sleeve 63 and exerts its force against the end of the nut 64 through a thrust washer 68. Movement of the nut B4 and gear 65 axially of the rod 59 is prevented by thrust bearings 69 xed on the rod 59 on opposite sides of the gear 65. Thus, when the bell crank 56 is oscillated counterclockwise (as viewed in Fig 8) it thrusts the rod 59 inward and thereby moves the taper slide inward, force being transmitted to the latter through the rod 59, thrust washer 69 and the gear and nut and collar assembly at the front of the slide (Fig. 4). Similarly, oscillation 0i the bell crank 56 in the opposite direction permits the taper slide 39 to move forward under the urging of the spring 6I on the rod 59.

In some instances the taper slide may be used to move the slides 49, 4l superimposed on it for some other purpose than in grinding a taper thread, as for example quick retracting the grinding wheel from the work or feeding the wheel toward the work. For such cases, rotation of the gear 55 is used to elect movement of the taper slide, as next described.

Rotation of the gear 65, by means to be described, will move the taper slide 39 rearwardly or return it to a predetermined position relative to the rod 59. The screw threads on the nut 94 and sleeve 53 preferably have a coarse pitch to produce movement through a fairly wide range by limited rotationof thegear `65. This movement by the gear 65 is incidental to and independent of movement transmitted to the taper slide by the sine bar through the plunger 54, bell crank t, rod 59, thrust washer lig and the gear, nut and collar assembly at the front of the taper slide. The wing unitv et limits the forward movement of the taper slide and when it is desired to render the sine bar ineiective, as in grinding straight threads, the wing nut may be turned to draw the holding rod 59 rearwardly against the tension of the spring 6i to a position in which the front end thereof cannot be engaged by the bell crank.

Movement of the taper slide 39 by rotation of the gear i5 and nut 6d is possible even when the rod 59 is retracted by the wing nut @il to disable the true taper controlling action of the slide, and consequently movement of the taper slide may be and is employed to shift the grinding wheel toward and away from the position to which the grinding wheel is adjusted ior the required size or depth of cut in the workpiece. In other words, the taper slide is used to withdraw the superimposed wheel slide di! as occasion may require but without disturbing the previous precision determined setting of the wheel slides own adjusting mechanism. Hence, when the taper slide is later restored to its initial position, the wheel slide will also be brought back without the necessity of regauging the position or the wheel on it relative to the taper slide and, hence, relative to the work.

The actuating means 36 for adjusting the grinding wheel to a position relative to the work, either byv taper or wheel slide movement, is best seen in Figs. 4, 8 and 14. Rotatably supported by bearings 8i on the plate l2 and a boss 8|ad on the front wall of the base is a shaft 82 which extends slidably and rotatably through the iront portion of the taper slide 39. Beyond the front wall oi the base, the shaft has a hand wheel 83 fixed thereto. Near its rear end the shaft has an elongated spur gear dfi thereon for engagement with a spur gear 85 on a lead screw S6 (Fig. 14) which extends rearwardly and is journaled as at 8l for rotation without axial play in a boss 88 extending upwardly from the tap-er slide 39. The rear end of the lead screw 85 is threaded inr `a nut 89 which is rotatably supported without axial p-layfby a boss 5d depending from the wheel slide dil. p

Rotation of the shaft 82 by rotation of the hand wheel '83 at the operators station will, through gears 84, 85, rotate the lead screw 88 in the nut 89 to move the wheel slide it transversely of the workpiece. This adjustment enables the operator to set the wheel slide 4d at the position which determines the nal or iinished size of the workpiece. The nut 89 has on its rear end a spur gear Si, the purpose of which will presently be described.

Associated with the size control shaft 82 is BI in the boss S'IEL on the base. VAt its rear :end within the'base the sleeve Io carries an elongated gear lill in mesh with the gear 55 carried on `the taper slide rod 59. Adjoining the hand wheel, an enlarged ring Ila is secured to the sleeve I 0G to support a hand lever H12 (Figs. 1 and d) by which the sleeve i, the gears IIJI, 65 and the nut del may be rotated to retract or advance the taper slidey td. Since the grinding wheel assembly 23 is mounted on the taper slide 39, such movement will vary the depth of the cut made by the grinding wheel in the workpiece. Thus, the grinding wheel may be quickly withdrawn from the work at the end of or during a cut for replacement of the workpiece or to dress the grinding wheel without altering or disturbing the initial adjustment for size obtained through shaft S2. Preferably, `suitable stops (not shown) are provided to limit the handle movements IElZ to an arc which will produce a travel of the taper slide only slightly greater than that necessary to retract the grinding wheel periphery to clear the greatest depth of thread which will be cut.

The grinding wheel assembly 23 includes a wheel head Mil (Fig. l2) in which the drive shaft 23 for the grinding wheel iii is journaled. The

wheel head is suitably mounted on a side of the wheel slide di! for angular adjustment of the grinding wheel in conformity with the helix angle of the thread being cut on the workpiece. The driving motors t, 2d for the grinding wheel shaft and the dressing device respectively are mounted on the wheel slide il@ near the rear end thereof. The dressing device is mounted on the dresser slide il behind the grinding wheel II I and the mounting includes a transverse slide H2 (Fig. 5) for properly alining the dressing devices with the edge of the grinding wheel.

Referring to Figs. 4 and 5, the manual adjusting means Si for the dressing device includes a sha-it i2l extending rearwardly from the Gperators static-n in front of the machine into the taper slide i where its rear portion is supported by spaced bearings I2! `on the plate t2. The shaft is rotatably and slidably supported by the taper slide 39 and operators hand wheel I'22 is secured to its iront end. Along its rear portion the shaft has an elongated spur gear I 23 engaged by a spur gear |24 secured to theA front end of a shaft |25 having a feed screw thread I2 formed thereon. The shaft IE5 is. rotatably supported `without axial play by bear ings I.2'I on the wheel slide dii. The feed screw manual control means for moving the taper slide 3S by rotation of the gear 65, this movement being utilized to retract the grinding wheel wholly or partially from a workpiece and to advance `the grinding wheel to engage the workpiece or to feed the grinding wheel incrementally into the workpiece until the grinding wheel has cut to the finished size determined by the preliminary setting of wheel 83. Thus, referring to Figs. 4 and 14, sleeve lili) encircles the front end of shaft 82 rearwardly of the hand wheel 83 and is elongated to extend through the front bearing be obtained by rotation IE6 is engaged by a nut t28 carried by an arnr I2@ depending from the dresser slide III. Thus movement of the dresser slide to eiect a dressing engagement of the dressing diamonds or the: like (one of which is indicated at 25a in Fig. 5) with the rear side of the grinding wheel i II may of the hand wheel i222 and any desired relationship may be maintained by suitable locking means Iiiil. i

For the convenience of the operator in setting up the machine from the left-hand end thereof, supplemental means for rotating the shaft I2!! may be provided. This means, as shown, comprises a cross shaft lei rotatably mounted on the base to extend from beneath the shaft I 2o through the'left end of the base. The outer end of the cross shaft has a hand wheel 32 thereon and the inner end carries a spiral gear I33 meshing with a similar gear i313 on the shaft The manual ladjusting means which have been described enable the operator to set the machine to cut to size or depth, to move the dressing device into dressing engagement with the grinding wheel, and to shift the grinding wheel and dressing device as a unit toward and away from the workpiece. Additionally, means is provided fo-r automatically compensating for the variation in the grinding wheel diameter resulting from the dressing operations, whereby to maintain constant the original setting determining the finish size or depth of cut.

Referring to Figs. 5, '7 and 8, the compensating means, according to the present embodiment, includes the following arrangement: The rear end of the dresser slide control shaft |25 has a spur gear |40 secured thereon which, through a pair` of intermediate pick-off idler gears |4|, |42 (Fig. 7), drives the gear 9| on the rotatable nut 89. This nut (as previously described) is rotatably mounted without end play on the wheel slide 4D and engages the feed screw threads on the shaft 86 carried by the taper slide. Thus, when the dresser slide 4| is moved toward or away from the grinding wheel the rotary movement of the shaft |25 also drives the nut 89 through gears |46, |4| and |42 to move the nut along the stationary shaft 86, thereby shifting the wheel slide 46 in the direction of the dresser slide movement. The arrangement is such that the wheel slide 46 is moved through the distance required to maintain the initial size or depth of cut relation between the grinding wheel and the work. In other words, when the dresser slide 4| moves relative to the wheel slide 4|), the wheel slide also moves an equal distance (carrying with it the dresser slide) to compensate for the reductio-n in wheel radius by the removal of material from the grinding wheel in dressing it. One of the idler gears lfil or |42 may be disengaged to enable the operator to adjust initially the dressing device along the wheel slide without movement of the latter.

The supporting and driving means for the workpiece includes means for rotating the workpiece and for translating it with a feed movement past the grinding wheel Also included is means actuated in timed relation to workpiece rotation for advancing and retracting the grinding wheel relative to the workpiece for relief cutting as, for example, in grinding taps or hobs.

eferring to the machine structure which supports and drives the workpiece, a plate |56 (Figs. and la) along the front side of the base has adjustable opposed V-shaped ways |5| which,

through interposed roller elements, support the workslide 41 for reciprocatory movement.

Extending upwardly and rearwardly from the left-hand end of the work slide 41 is a pedestal |52, the purpose of which will be presently described. The upper surface of the work slide is provided with ways |53 for adjustably supporting the tailstock 22. The headstock or work head structure 2| includes, as may be seen in Figs. 1, 2, 3, 9 and l0, a housing |55 is supported by side and bottom guideways |55 on the base for adjustment along the line of movement of the work slide. Suitable lock means |51 (Fig. 9) secure the work head in an adjusted position. To maintain the driving belt 32 taut in the various positions of adjustment of the workhead, such means as an adjustable idler pulley 33a (Fig. 2) may be employed.

The shaft 34, as shown in Fie. 10, extends into the lower portion of the housing |55 and is rotatably supported therein by spaced bearings |58.

Centrally of the housing the shaft 34 has a worm |59 keyed thereto for engagement with the worm wheel |66 secured to a ange |6| on an elongated sleeve |62, which slidably encircles the work shaft 35. Such means as a sliding feather key |63 drivingly connects the sleeve and shaft. One end of the shaft 35 (the right-hand end as shown in Fig. 9) extends through a dust seal |64 at the end of the sleeve and is supported by combined radial and thrust bearings |65 in a housing |66 which is secured to the end of the pedestal |52. A live center |51 on the shaft 35 extends beyond the housing |66 for engagement with the workpiece.

At its opposite end the shaft 35 (Fig. 9) is of reduced diameter to receive an elongated sleeve or shell |63 which is keyed to the shaft as at |69 and is detachably secured thereon by cap screw and washer means |10. The external surface of the collar |68 has precise lead screw threads |1| therein and the sleeve illustrated is one of a series of interchangeable sleeves which differ from each other in the pitch of the thread either in. a right-hand or left-hand direction. A slidable nonrotatable frame |12 has secured thereto, as shown in Fig. 1l, a split nut |13 constituting a master lead nut engageable with the lead screw on the sleeve |68. The nut is also interchangeable. Fixed on the inner end of the frame is a centrally apertured disk |14 through which the shaft 35 extends. A flanged collar |15 encircles the shaft 35 and extends through the aperture in the disk |14 to dispose the collar flange |16 behind the disk. Between the disk |14 and the flange is a thrust washer 11 and on the other side of the disk is another thrust washer |18 abutted by a spacing ring |19 in turn engaged by a ring |86 carrying a worm gear lill. A nut |82, engaging external screw threads on the collar |15, frictionally engages the ring to establish a driving relation between the worm wheel |8| and the collar |15, as. well as to bind the disk |14 between the thrust washers |11, |18 and against the flange |16. External screw threads on the collar |15 enga-ge an internally screw threaded member |83 which is fixed to the housing |55. The worm wheel i8! is engaged by a worm |84 on a shaft |85 which is journaled on the housing and extends through the front side thereof, and a wheel |86 having an operating handle |81 is secured to the front end of the shaft. The nu.. meral |89 (Fig. 9) designates bearings in the housing |55 for supporting the shaft 35 and its associated mechanism.

In operation, the housing |55 is adjusted longitudinally of the base to dispose the workpiece between the head and tailstock centers substantially in proper relation to the grinding Wheel. A more accurate relation is obtained by rotation of the wheel |86 which, through shaft |85, worm |84, worm wheel |8|, rotates collar |15 to shift it longitudinally of the work head casing |55. Since the sliding frame |12 is connected through disk |113 with the collar |15, axial movement of the latter will shift the frame |12, thereby moving the master lead screw and nut and the shaft 35 axially. Such axial movement of the shaft 35 is transmitted to the worktable and tailstock thereon through the pedestal |52 to adjust the position of a workpiece mounted between the head and tailstock centers with respect to the grinding wheel. The means just described, after the initial adjustments have been made, is used to pick up the lead on successive workpieces at the beginning of a cutting operation.

The same mechanism has a further purpose. Machines of the type here under consideration may be arranged to perform a cutting operation during movement of the workpiece past the grinding wheel in either direction. It is impossible to eliminate entirely backlash or play in the mechanism which feeds the workpiece and compensation must be made for such backlash-at the beginning of each reversal' of movement. The means for shifting the shaft 35 axially isused to compensate for backlash. Thus, a pair of stops E90 (Fig. 1) mounted for adjustment along an arcuate slot I9! on a bracket |92 adjacent to the periphery of the wheel I 86 limit the movement of a pin It projecting radially outwardly from the wheel. By properly determining the amount of backlash in any given assembly and by adjusting the stops i90 to limit movement of the wheel 89 through an arc which will produce a commensurate backlash compensating movement of the shaft 35, the operator need only rotate the wheel H30 from one stop to the other at each reversal.

The means in the present machine for moving the grinding wheel for relief or backoff grinding of such cutting tools as taps, hobs, and the like, will be described with reference to Figs..2, 3, 9, i2, 13 and 14.-. As shown in Fig. 9, the collar |62, through which the shaft 35 is driven, has a series of cams 200, 520i, 202 keyed thereto externally of the housing Iii-5 and held in place by a nut 203. These cams may be termed relieving cams and are formed with various numbers to the number of flutes which are to'be relief ground. The cams moreover are Shaped to pro. duce the required movement Vof the grinding wheel.

Referring to Figs. 2 and 3, a rock shaft 205 is mounted to extend along and below the work head `i555 in a direction parallel to the line of adjustment of said head. Siidably mounted on the rock shaft 205, as by a feather key, is an upstanding lever 20'?. Suitable means, not shown, is provided for securing the lever to the rock shaft at various positions along the length thereof. Pivoted intermediate the ends of the lever 20? is an arm 208 which extends upwardly at an acute angle to the lever. A cam follower 200 is mounted on the upper end of the arm 200 for engagement with one or another of the relieving cams 290, 20I and 202, as determined by the position of the lever 201, on the rock shaft 205. Pivoted on the upper end of the lever 201 is a bell crank lever having a long arm 210 upstanding to provide a handle and a short arm 2i I extending toward the cam follower arm 208.

The end of the arm 2 I I is connected by a link 252 with the arm 208 to provide a toggle. The arrangement is such that when the handle arm 2MB of the bell crank lever is in its forward position (toward the right in Fig. 2), the toggle is extended with the center pivot of the toggle slightly past dead center. In this relationship, movement of the cam follower arm 208, produced by the cam with which the follower 209 is associated, will be transmitted to the lever 201. Rearward movement of the handle 2I0 will break the toggle alinement and withdraw the cam follower 20S to an inoperative position.

The cam induced movements of the work shaft 255 are transmitted to a second shaft 2I3 by means which is adjustable through a wide range to determine the ratio of movement between the rock shafts 2G15 and 2id, as well as the rotative position of the rockt shaft 2I3. The rock shaft of lobes equal- 2I3 is journaled on the machine base to extend longitudinally thereof to a. position beneath the grinding wheel spindle assembly.` On its outer or left-hand end the shaft has an arm 2 I4 secured thereto. A section 2I-5 of an extensible link 2|6 isarranged to lbe adj-ustably secured to the arm along the length of an arcuate slot 2I'I therein. The other section 2li! of the linkv ZIE has an ad- `instable connection with a slotted arm 2 I 9 secured to the rock shaft 205. By adjustment of the length of thelink 2I6 and the relationship of the ends of the link to the arms 2| 4 and 2I9 substantially any required movement of the rock shaft M3 may be obtained. Springmeans 2| 4a connected'to the end of the lever 2l4 and to the base exerts a force in a direction tending to hold the cam follower 209 in cam engagement.

This movement of the rock shaft 2I3 advances or retracts the grinding wheel relative to the workpiece and in timed relation to the rotational movement of the workpiece. Referring to Figs. 12, 13 and le, the grinding wheel spindle or drive shaft 23 is supported by bearings 220 in a spindle casing 22I which extends through an eccentric bore in a carrier 222. The carrier is supported for oscillatory movement by the wheel head H0. The wheel head has a circumferentially extending slot 223 (Fig. 13), and the short end of an angular arm 224 rigid with the carrier 222 extends through the slot. The outer longer end of the arm extends along the wheel housing and at its end has a ball and socket connection indicated at 225 with the upper end of a link 226. The link is adjustably secured atits lower end to an arm 227i fixed on the rock shaft 2I3. Hence, rocking movement of the shaft 2I3 will oscillate the carrier 222 which movement, because of the eccentric relation of the shaft 28 to the carrier 222, will produce a desired reciprocatory relieving movement of the grinding wheel with respect to the workpiece.

Automatic cycling apparatus Provision has been made for operating the machine described above entirely automatically. In brief, the controls are such as to execute an automatic cycle in which:

.(o) The work slide 41 is transversed back and forth to move a corresponding portion ofthe workpiece past the engaging grinding wheel with a dwell at the end of each stroke of the work slide.

(b) During the dwell period at the end of each work slide stroke the taper slide 30, and the wheel slide iii on it, are fed forward a predetermined increment of distance to increase the depth of cut during the succeeding pass of the work.

(c) After incremental infeeding of the taper slide has reached a predetermined total, the dresser mechanism 25 is fed a predetermined increment of distance, and a cycle of operation for the dresser instituted.

(d) At the conclusion of the dresser operation, the dresser mechanism comes to rest and the wheel slide 40 is fed to nal depth, and the work slide 4l is given an additional traverse for finish grinding. 1

Reference has heretofore been made to four motors included in the machine, namely, the work feed-motor 3i, the dresser drive motor 29, and the grinder drive and coolant pump motors 20 and 20a. In addition, two further motors are provided for use during automatic operation, these being a grinder wheel feed motor 250 and a dresser feed motor 25|. If desired, a-refrigerator motor and a suction fan motor may also be provided. In brief, the grinder feed motor 250 is used to turn the sleeve |06, heretofore noted (see Fig. 4) in a direction to feed the grinding wheel toward the work. This feeding is accomplished in successive increments. The dresser feed motor is used to turn the shaft to feed the dresser mechanism an amount required to dress down the wheel for the nal grinding pass.

To correlate the operation of all six motors noted above in an integrated system so that the various elements of the machine will be operated in proper timed relation, a series of machine element-operated, or so-called limit switches, are utilized.

Before proceeding to a description of the control circuit through which the various motors and element-operated switches are interrelated,` attention will be given to the details of the mechanical connections between the motors 250, 25| and the parts which they operate. First, as to the grinder feed motor 250 (see Fig. 19) it is to be noted that, in general, it operates through a rack and pinion arrangement to drive a ratchet mechanism which in turn steps the sleeve |66 around step by step for successive increments of infeed for the grinder. For this purpose, the motor 256 is connected through a speed reduction gearing in a casing 252 to revolve a stroke disk 253 one full revolution for each increment of infeed. The stro-ke disk has on it an eccentric crank pin 254 by which it is connected to a reciprocable member made up of two sections 255 and 256, the outermost one having rack teeth 251 on it. The two sections 255, 256 are yieldably joined by means including a rod 258 extending through a longitudinal bore in the section 256 and anchored at the outer end to the section 255. At the outer end of the rod 258, a helical compression spring 259 encircles it and is interposed between the outer end of the section 256 and a nut 260 on the end of the rod. A housing 26| having a portion encircling the end of the bearing 8|, which receives the sleeve 00 (see also Fig. 16), .1.

presents a throat 262 receiving the rack section 256 and has rollers 263 journaled in it and on which the member 256 runs. The rack teeth 251 mesh with pinion teeth 264 on a shaft 265 (Figs. 16 and 19) to revolve the latter as the rack reciprocates.

At its opposite end, the shaft 265 has a second set of pinion teeth 266 (Figs. 16 and 18) meshing with a toothed 'sector 261 of a spider 258 loosely journaled on the sleeve |06. This spider 268 car- 5;

ries a pawl 260 engageable with a sector of ratchet teeth 210 on the periphery of a collar 21| fixed to the sleeve |66. Each stroke of the pawl 269, effected by a stroke of the feed motor-driven rack Z- 256, causes the pawl 260 to engage the teeth 210 and advance the sleeve |00 a predetermined incremental distance. The amount of such advance for the sleeve |00 for each stroke of the pawl 269 is determined by the setting of an adjustable guard sleeve 212 encircling the ratchet-toothed collar 21| and having an opening 213 in it (see Fig. 18) through which the ratchet teeth 210 are exposed. The guard 212 is adjustable about the axis of the sleeve and can be locked in adjusted position on the collar 1 |060. (see Fig. 16) by locking means indicated as 214. By changing the rotational setting of the guard 212, the number of ratchet teeth advanced by the pawl 269 during each stroke of the latter is controlled.

The stroke disk 253 driven by the grinder feed motor (Fig. 19) also has a cam lobe 215 on it for actuation of the limit switch LS1 which operates, in a manner hereinafter described, to stop the motor 250 at the end of each full revolution or feed cycle of the stroke disk 253. In Figs. 18 and 19, the parts are shown in the positions which they occupy after the stroke disk has made onehalf of a. revolution, being in effect, stop-motion views.

Turning now to the motor 25|, it should be noted, in general, that it is available to operate the sleeve |00 for a quick retract motion of the grinding Wheel, and also to feed the dresser mechranism 25 a predetermined increment of distance necessary for dressing the grinding wheel.

However, the retract motion can be disabled at the will of the operator so as to employ the motor only for dressing feed.

Considering first its mechanical connection for effecting a quick retract turn of the sleeve |00, it should be observed that the motor 25! drives a stroke disk 266 (Fig. 15) through a speed reduction gearing in a casing 28|, the disk being revolved one full revolution for full retraction of the taper slide 39. This stroke disk is connected by an eccentric crank pin 282 with a link 233, which is in turn pivotally connected at its outer end with a reciprocable rack 284. For each cycle of operation the motor 25| turns the stroke disk 266 one full revolution in a clockwise direction from the position shown, this latter position being that which the parts occupy at the completion of the infeeding movements eifected by the feed motor 250 as described above and just prior to instituting of retraction. The rack 284 slides in a stationary housing 285 (see Fig. 16) on rollers 286 and meshes with a pinion 281 on a shaft 288 which is revolubly journaled on the housing 285. Loosely journaled on this shaft is a disk 289 having a sector of teeth 296 thereon (see Fig. l5) meshing with a sector of teeth 29| on the ring llllct fixed to the sleeve |66 as heretofore described. Accordingly, when the rack 234 is drawn to the right (as viewed in Fig. 15) by a clockwise rotation of the stroke disk 266, the disk 289 is oscillated counterclockwise through the engagement of a pawl 262 on it with a notch 293 in a disk 226 fixed to the shaft 286 which carries the pinion 281 (see also Fig. 16). As a result the ring |06a, and attached sleeve |69 are revolved clockwise to fully retract the grinding Iwheel. This retraction movement is, of course, effected in the same manner as when the hand lever |62 is swung to the right from the position shown in Fig. 1.5 as described heretofore in connection with the manual operation of the machine.

The rack 284 also serves to revolve a second pinion 295 (Fig. 15) for turning the dresser feed shaft |20. The pinion 295 is journaled in a housing 2-96 (see also Fig. 17) which receives the rack 284 and has in it a roller 291 on which the rack rides. The pinion 295 in turn meshes with a segment of teeth 298 on a collar 299 encircling the stationary head 306 in which the dresser feed shaft |20 is journaled. On this collar 299 is a pawl 36| (Figs. 15 and 17) engageable with a segment of ratchet teeth 362 on a hand wheel |22. Consequently, each stroke of the motor driven rack 284 causes the pawl 36| to advance the hand wheel |22 a predetermined increment of distance for effecting a corresponding feeding motion of the dresser mechanism 25.

When the shaft |20 is turned, as described 

